4592sēmeíon – a sign (typically miraculous), given especially to confirm, corroborate or authenticate. 4592/sēmeíon ("sign") then emphasizes the end-purpose which exalts the one giving it. Accordingly, it is used dozens of times in the NT for what authenticates the Lord and His eternal purpose, especially by doing what mere man can not replicate of take credit for.

1. universally, that by which a person or a thing is distinguished from others and known: Matthew 26:48; Luke 2:12; 2 Thessalonians 3:17; σημεῖονπεριτομῆς (explanatory genitive (cf. Buttmann, § 123, 4)), equivalent to σημεῖον, ὁἐστιπεριτομή, circumcision which should be a sign of the covenant formed with God, Romans 4:11; τάσημεῖατοῦἀποστόλου, the tokens by which one is proved to be an apostle, 2 Corinthians 12:12; a sign by which anything future is pre-announced, Mark 13:4; Luke 21:7; τόσημεῖοντῆςσήςπαρουσίας, genitive of the object, Matthew 24:3; τοῦυἱοῦτοῦἀνθρώπου, the sign which indicates that the Messiah will shortly, or forthwith, come from heaven in visible manifestation, Matthew 24:30; with a genitive of the subjunctive τάσημεῖατῶνκαιρῶν, i. e. the indications of future events which οἱκαιροί furnish, what οἱκαιροί portend, Matthew 16:3 (T brackets WH reject the passage); a sign by which one is warned, an admonition, 1 Corinthians 14:22. used of noteworthy personages, by whom God forcibly admonishes men and indicates to them what he would have them do: thus σημεῖονἀντιλεγόμενον is said of Jesus Christ, Luke 2:34; ἸωνᾶςἐγένετοσημεῖοντοῖςΝινευίταις (Jonah 3:4), Luke 11:30; hence, τόσημεῖονἸωνᾶ, Luke 11:29, is equivalent to τόσημεῖον like to that ὅςἦνἸωνᾶς, i. e. to the sign which was given by the mission and preaching of Jonah, to prompt men to seek salvation (Winer's Grammar, 189 (177)); in the same sense, ὁυἱόςτοῦἀνθρώπου says that he will be a σημεῖον, to the men of his generation, Luke 11:30; but in Matthew 12:39; Matthew 16:4τόσημεῖονἸωνᾶ is the miraculous experience which befell Jonah himself, cf. Matthew 12:40; that Luke reproduces Christ's words more correctly than Matthew is shown by De Wette and Bleek on Matthew 12:40, by Neander, Leben Jesu, p. 265f edition 1 (English translation, (3rd edition N. Y. 1851) § 165, p. 245f), and others; (but that Luke's report is less full than Matthew's, rather than at variance with it, is shown by Meyer, Weiss, Keil, and others (on Matthew, the passage cited)).